zentao/tmp/model/open/rnd/admin.php

<?php
global $app;
helper::import($app->getModulePath('', 'admin') . 'model.php');
class extadminModel extends adminModel 
{
public function getXxcAllFileSize()
{
    return $this->loadExtension('xuanxuan')->getXxcAllFileSize();
}
//**//
}